In recent years, along with a miniaturization, weight reduction and lowering prices of an image capturing apparatus such as a digital camera, a still camera and a video camera, the image capturing apparatus has been equipped to various appliances such as a cellular phone, a laptop computer, a Personal Digital Assist (PDA) and a wearable display. In particular, a camera-equipped cellular phone has been rapidly available for use because of the miniaturization, portability and convenience that an image can be sent for communication on the spot where the image is captured.
While such camera-equipped appliance allows a user to capture an image easily at anytime and anywhere, there is a problem of invasion of privacy that a person to be a subject of an image capturing is captured without noticing that his/her image is being captured. Also, there is a problem that, even in a region where photographing is prohibited such as in a museum, an unauthorized image capturing can be performed easily without being noticed by anyone because of the portability.
In order to solve the problems, various measures have been taken using conventional technologies. For example, there is an invention that a tally light which generates light from a light source and which has passed a color filter is set in a camera-equipped portable terminal and the tally light is turned on when the camera starts capturing an image so that the subject can recognize that his/her image has been captured (e.g. refer to Japanese Laid-Open Patent Application No. 2002-374444). Also, there is an image capturing apparatus which has an unauthorized image capturing prevention information detection unit outputting an unauthorized image capturing prevention signal which turns off an image capturing function when an unauthorized image capturing prevention information generation apparatus detects unauthorized image capturing prevention information having predetermined features (e.g. shape, and flashing pattern) from an image signal obtained from the captured image. Therefore, the subject carries the unauthorized image capturing prevention information generation apparatus so as to prevent the unauthorized image capturing (e.g. refer to Japanese Laid-Open Patent Application No. 2001-169175). Also, a current camera-equipped portable terminal is designed to prevent an unauthorized image capturing by making sound for notifying photographing when an image is captured.
However, the method disclosed in Japanese Patent Publication No. 2002-374444 and the current widely used method of notifying photographing with sound cannot prevent capturing an image of a subject from a distant location using a telephoto lens, an electronic zoom and the like. Further, these methods emit light or make sound every time when an image is captured. Therefore, they cause an inconvenience to people around an image taker when the image capturing is authorized.
In addition, the method disclosed in Japanese Laid-Open Patent Application No. 2001-169175 uses whether unauthorized image capturing prevention information such as a predetermined shape and a flashing pattern is included in the captured picture. However, it is not certain whether such unauthorized image capturing prevention information is captured depending on the condition therein. For example, assuming a case where a subject equips an unauthorized image capturing apparatus on the chest. Herein, in the case where the subject is captured at a moment when the subject is about to look back, the face of the subject is shown in the captured picture. However, the unauthorized image capturing prevention information is not shown so that the unauthorized image capturing cannot be prevented.